Liquid–liquid equilibria of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate and sodium citrate/tartrate/acetate aqueous two-phase systems at 298.15 K: Experiment and correlation

Binodal curves of the aqueous 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) + sodium citrate (Na3C6H5O7), [Bmim]BF4 + sodium tartrate (Na2C4H4O6) and [Bmim]BF4 + sodium acetate (NaC2H3O2) systems have been determined experimentally at 298.15 K. The Merchuk equation was used to correlate the binodal data. The effective excluded volume (EEV) values obtained from the binodal model for these three systems were determined. The binodal curves and EEV both indicate that the salting-out abilities of the three salts follow the order: Na3C6H5O7 > Na2C4H4O6 > NaC2H3O2. The liquid–liquid equilibrium (LLE) data were obtained by density determination and binodal curves correlation of these systems. Othmer–Tobias and Bancraft, and Setschenow equations were used for the correlation of the tie-line data. Good agreement was obtained with the experimental tie-line data with both models.